<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .image{
      width: 300px;
      height: 300px;
      background-color: lightblue;
    }
    .photo{
      width: 100px;
      height: 100px;
      background-color: lightcoral;
    }
  </style>
</head>
<body>
  <section class="show">
    <div class="tshirt">
      <div class="image"></div>
      <div class="empty"></div>
    </div>
  </section>
  <section class="patterns">
    <div draggable="true" class="photo">图案1</div>
    <div draggable="true" class="photo">图案2</div>
    <div draggable="true" class="photo">图案3</div>
    <div draggable="true" class="photo">图案4</div>
    <div draggable="true" class="photo">图案5</div>
  </section>
  <script>
    document.addEventListener('dragstart',e=>{
      e.target.style.boder = '5px dashed red'
    },false)
  </script>
</body>
</html>